The current state of the art in-line flow regulator used has a fixed orifice as the regulating port to control the flow in this valve. This fixed orifice is installed at the factory and can not be changed in the field. Because of this type of installation, the valve must be ordered from the factory stating the flow that you wish to have regulated. The problem with this method of manufacturing the valve is that you must know the actual flow rate that you need and then have the time to wait for the factory to manufacture the valve from scratch. This also means that the distributor will not stock the valves because of the number of different flow rates required and the distributor would have to stock for each of these different flow rates. This method can also be a problem with an end user who did not calculate his flow rate exactly to his requirements, or his requirements changed slightly, therefor requiring a different flow rate than the valve he received. He must now go back through the whole process and reorder a new valve from the factory with a different flow rate he requires. This whole process can be very discouraging to both the distributor, who is trying to supply the valve to the end user, and the end user, who has delivery problems and other problems associated with getting this valve.